When designing transducers (e.g. sound transducers), such as pressure sensors, acceleration sensors, microphones, or loudspeakers, it may be typically desirable to achieve a high signal-to-noise ratio (SNR) of the transducer output signal. The continuous miniaturization of transducers may pose new challenges with respect to the desired high signal-to-noise ratio. Microphones and to some extent also loudspeakers, which may be used in, for example, mobile phones, laptops and similar (mobile or stationary) devices, may nowadays be implemented as semiconductor (silicon) microphones or microelectromechanical systems (MEMS). In order to be competitive and to provide the expected performance, silicon microphones may need high SNR of the microphone output signal. However, taking the capacitor microphone as an example, the SNR may be typically limited by the capacitor microphone construction and by the resulting parasitic capacitances.
Parasitic capacitances are usually unwanted capacitances interfering with capacitances between both the membrane and the counter electrode. Hence, capacitance values, intended to be transferred into electrical signals responsive to the movement of the membrane are interfered. In case the MEMS device is embodied as a double backplate microphone, for example, parasitic capacitances may influence the MEMS device such that the electrical output signal does not provide a sufficiently correct reproduction of the audible sound input signal, i.e. the arriving sound waves.